System of electrical selection.



N. L. TOLVSTAD.

SYSTEM OF ELECTRICAL SELECTION.

APPLICATION FILED AUG. 16, 1907.

Patented Aug. 18, 191i 6 SHEETS-SHEET 1.

INVENTOH NELSON L- TuLvsTAn ATTORNEYS THE RORRIS PETERS 60.. FHom-LITHQ,WAsHINOmN. D. c

N. L. TOLVSTAD.

SYSTEM OF ELECTRICAL SELECTION.

APPLICATION IILED' AUG. 16, 1907.

1,1 08,028. Patented Aug. 18, 1914.

6 SHEETS-SHEET 2.

THE NORRIS PETERS c014 PHGTO-LITHO., WASH NGTUN. D. C.

N. L. TOLVSTAD.

SYSTEM OF ELECTRICAL SELECTION.

APPLICATION FILED AUG. 16, 1907.

1,108,028. Patented Aug.- 18, 1914.

6 SHEETS-SHEET 3. 64 '4 1 6- (l/ 1 I {1/ 5 ff- 1 (.7 t 5 W I W. 6.

WITNESSES INVENTOH y iw- NEI;:DNL TULV5TAD a x W ATTORNEYS N. L.TOLVSTAD.

SYSTEM OF ELECTRICAL SELECTION.

APPLICATION FILED AUG. 16, 1907.

Patented Aug. 18, 1914.

6 SHEETSSHEET 4.

INVENTOH NELSDN L TEILV5 TAD W/ TNE SSE S N. L. TOLVSTAD.

SYSTEM OF ELECTRICAL SELECTION. APPLIOATION FILED AUG. 16, 1907.

1, 1 08,028. Patented Aug. 18. 1914.

6 SHEETS-SHEET 5.

g 7 W I P ATTORNEYS THE moi-Wis PETERS (30.. PHOTO-LITHO. WASHINGTON, o.1:.

N. L. TOLVSTAD.

SYSTEM OF ELECTRICAL SELECTION. APPLICATION FILED AUG. 16, 1907.

1,108,028. Patented Aug. 18, 1914.

6SHEETSSHEET 6.

I] IL I 7 III.

4 & fi Ill 0 & I

a 2% v Z0- WITNESSES nvvElvrofl NEL s cm L- TDLVS TA'IJ A TTOHNEYS' rIrENORRIS PETERS 60.. PHOTO LIFHO. WASHINGTON. u c.

UNITED STATES PATENT v(,.. Jnn0E.

nnnson L. ToLvsT-nD, on GnoToN, socrn pnno'rn.

.SYSTEM OF ELECTRICAL SELECTION.

Specification of Letters Patent.

Patented. Aug. 18, 1914.

Continuation of application ,Serial No. 339,743, filed October 20,.1906. This application filed August 16,

1907. SeriaI No. 388,914.

To all whom it may concern Be it known that I, NELSON L. TOLVSTAD, acitizen of the United States, and resident of Groton, in the county ofBrown and State of South Dakota, have invented an Improved System ofElectrical Selection, of

which the following is a specification.

' such circuit; second, the connection of a suitable current source toeach of the said cross shunts and means for directing the cur-' rent toeither side of such circuit, as well as means for cutting outintervening cross shunts, together with their respective resistances inthe main circuit between applied current source and the point of thecircuit such current is desired to reach; third, the means for restoringthe circuit, or the part of the same which has been employed, to itscondition of rest.

In my invention, hereinafter described, claimed and shown in theaccompanying drawings, which are mostly diagrammatic-a1 in their natureand in which corresponding parts are indicated by the same characters ofreference throughout the several figures, I

do not wish to be limited to the exact form,

proportions, or mode of combination as may be described or shown, butreserve the right to make such changes, uses and combinations of thedifferent parts of the same as do not depart from the spirit of theinvention and the scope of the appended claims will allow.

In the drawings, Figures 1, 2 and 3 show diagrams of diiferent forms ofa main circuit combined with resistances and auto matic shuntingdevices. Fig. 4 is a diagram showing fundamental principles. Fig. 5 is adiagram showing one of the cross shunts of a circuit and itsconnections, opened or cut out by an inductively operated switch withcurrents of either polarity. Fig. 6 shows a part of acircuit in whichone of the main branches consists of a couple of conductors and. a crossshunt from each member altermg a polarized switching device. 10 is shownthe two members of the couple which one of the said members restores theother. Fig. 7 shows one of the cross shunts tl1e same as Fig. 5, butemploying a polarizecl switching device and is provided with polechanging circuit and current transmit ting keys. Fig. 8 shows thepolarized switching device. Fig. 9 1s a diagram showmg a portion of a crcuit employing two conductors for one of the main branches, alternating with each other through their respective cross shunts in theirconnection with the other main branch, like Fig. 6, but employ- In Fig.

with a single cross shunt, common to both,

switched from one tothe other of the said vmembers, and one restoringthe other. Fig. 10 is a detailed view of the relay operated switching orcontact lever and its connections. l f

In an electric circuit as mentioned and hereafter described (consistingof two and c to whichthe terminals of such cross shunt Z) are connectedin connection with an impedance or resistance coil in the circuit of thema1n branch a on each side of its unction with the cross shunt 5; suchpair of re-' sistance coils e 6, one on each side of the crossshunt b,is wound for equal resistance upon the soft iron cores d d between whichis placed a swinging or vibrating soft iron armature f. The said softiron cores (1 d with their coilse e and the terminal contact points ofthe same, have a different relative position to that of its armature fin the three diagrams shown, but the functions and operations of eachare essentially the same for the three forms of such resistance deviceas thereinshown. The form ofthe said resistance device shown by Fig. lis simple and center of motion in its vibrations between the twooppositely placed cores (Z (Z. WVhen thatpart of the circuit in whichsuch resistance device is located is at rest, the armature f shouldoccupy its middle or perpendicular position as shown, to which positionit is restored after each time it has been in use, by means which willbe shown later; and one method employed to make the middle position ofsaid armature f stable, is shown in Fig. 2, and which will be furtherexplained. In its extreme positions on either side of the perpendicular,as indicated by dotted lines, the armature f is held b its weightagainst the terminals of the siort branches 9 g on either side. Fromthis it will now be apparent that the armature f, when thrown over intoeither of its extreme positions, its contact with the short branch g,and its connect-ion at its lower end to the shunt 6, short circuits thecoil 0 in the main branch (4 on that side of its connection with thesaid cross shunt 6, while the other coil 6 on the other side of saidcross shuntremains in the circuit; and that, with the said armature f inits middle or neutral position, and with the current strength and theresistance of each of said coils e e so proportioned that enough currentis allowed to pass through one of the said coils (and through the crossshunt b) to energize its core 0? sufliciently to attract the armature fupon the arrival of a current from either side of the main circuit a 0such current will first pass through the first one of said coils and byattracting the armature f to make contact with the said branch 9 on thatside of cross shunt Z), the circuit will be instantaneously cleared fromthe resistance of such coil 6 for the passage of such current throughthe said cross shunt b; and further, that the second coil of the pairremaining in the main branch a in the circuit behind the cross shunt 6,together with the first coil of the pair belonging to the next similarcross shunt on that side of the circuit (as will be better understoodfrom Fig. 4) no appreciable amount of such current will be allowed topass on over the circuit to cross over at the next cross shunt.

As will be shown later, each of the cross shunts in a circuit as hereindescribed, may have in connection a generator for selecting or othercurrents, and the said armature f may then be employed to performanother function'than the aforementioned, namely, in selecting the sideof the circuit to which such currents are desired to be sent, which is amanual operation, simply throwing the said armature f over to that side,thereby shunting the coil 6 on that side of the cross shunt 5, thusclearing the circuit of this resistance on that side, while on the otherside there remain, as before explained, two such coils interveningbetween cross shunt Z) and the next cross shunt in the circuit on theopposite side. This will be further shown, as well as means for lockingthe said armature f in its position after having selected the de siredside of the circuit when any currents generated at this point of suchmain circuit are desired to be sent.

With the foregoing description of Fig. 1, the form of the same deviceshown in Figs. 2 and 3 will be understood. In Figs. 2 and 3, the cores(Z and the armature f between, and parallel to each other, and one orboth ends of said cores (Z shaped so as to shorten the air gap in themagnetic circuit between each of the said cores (Z cl and the armaturef, thus requiring a smaller current flowing through the said coils e eto operate it, or, what is the same, a proportionately higher resistancemay be employed and can be made effective in the circuit by the saidcoils e 6.

In Fig. 2 the middle position of the armature f is made stable by makingthe lower end square or concave, shaping this end to the form of anarrow base resting or rocking to either side in the flat bottom of aretaining seat it, which electrically connects with the embraced end ofthe armature f and the cross shunt b and the main branch (4 at a pointbetween the coils e e.

In Fig. 3 is shown a form of the resistance device employing a pendentarmature 7 pivoted and making electrical connection with the main branch0 at its upper end, the middle or neutral position being insured by itsweight, and swinging pendulum like to either of its contact positions onboth sides by the attraction of one or the other of the two cores (Z (Z,contact being effected through either of the two springs g g which holdthe said armature f in its shunting position when once attracted to thatside. The said springs g g are made of steel or iron, and the restoringof the armature f, in this form of the device, is effected by releasingthe frictional engagement of said springs g 9' against said armatureThis is effected by an electromagnet a" in an independent batterycircuit 2' through which a current is allowed to pass when restoring ofthe said armature f is desired, the said electromag net 2" attractingthe said springs g g, and releasing the armature f, which falls to itsmiddle position. out of contact with the said springs g (7, which willbe further shown later. In other respects, the functions and operationsare the same has been described in connection with Figs. 1 and 2; andeither form of the device as may be most suitcbly employed can be used,although for convenience for the purpose of illustration, I may in thefollowing mostly show the resistance device in the form shown in Fig. 1.

Fig. t is a diagram showing an electric circuit which may be composed ofany nun ber of cross shunts (five such cross shunts being shown in thediagram) connected at their respective terminals to the main branches (4and 0., At their iunction with the mam branch (1, each ofsuch crossshunts 6,6, 6 etc., is provided with a pair of re-' sistance coils, suchas ust described in the circuit of the main branch a, one of such shownand described; In Fig. 4 each of the several cross shunts Z), Z), 6etc.-, are also shown provided with a current generator B, B, B etc.,being inthis case a battery which may be switched into the circuit "ofthe sameby their'respective contact keys is, 7c, 70 etc., wherebycurrents may be sent into the main circuit from any of thesaid crossshunts comprised in such circuit, andto the right or left hand of thecircuit as may be desired. .The method employed, as has been stated, isto throw the shunting'armature. f of the resistance device A of thatparticular cross shunt in which such current is generated, over into itsshunting position on the side of its resistance device it is desired tosend such current, thereby shunting its resistance coil out of thecircuit on that side of its connection with said cross shunt.

If, we will say, that part of the circuit in which the cross shunt b islocated is in its normal condition-ofrest, that is, with the resistancedevice of the cross shunt and also those of the adjoining ones, 6 and 5on either side of it, in the circuit-with their respective shuntingarmatures f in their middle or neutral position, and the currentgenerator or batteryB is switched into the circuit of the cross-shunt bby depressing the key if, sendingor attempting to send a current. intothe circuit from this point, it

will be seen that the condition of the circuit.

on both sides of it is alike and that half of the current wouldfiow ortend to flow to the right and return through the cross shunt b and theother halfof such current tend in the same way, to return through thecross shunt b at the left; but the combined re- I sistance in the.circuit of the coils eiand 6 intervening between the current source andthe cross shunt b to the right, and the coils 6* and e to theleftissufliciently high to prevent any part of such current, practiscally speaking, from passing in either direction. But, as intimated, itwas desired from the cross shunt b to prepare the ad-' jacent part ofthe circuit for the pass'ageof currentsfrom the cross shunt b to any ofthe other cross shunts in such circuit, either to the ri ht or left handside of the'same,

and this is effected by shunting the intervening resistance coils out ofthe circuit in thedirection in which such circuit is desired to beemployed. If this direction is to the left, then, by first'throwing thearmature f of the resistance device A over to its shunting position tothe left, as indicated by thedotted line, thereby shunting the coil 6out of the circuit and now depressing the key 71: connecting thegenerator branch of the cross shunt b with the main circuit, itscurrent" generator or battery B is now able to overcome the remainingresistance a as was explained," and attract its shunting armature f,which is thrown over into the position, which is indicated by the dottedline, shunting the coil 6 out of the circuit also, and the circuit isnow cleared of all interposed resistances to the passage of a currentover that part of the same consisting of the cross shunts b and b andthe intervening parts of the main branches a and c, to which part ofthesaid circuit such current will be confined by the two resistance coilsremaining between this part of the circuit and the adjacent cross shuntsb and b on both sides.

It will now be evident that if it had been desired to prepare thecircuit to the right, instead of throwing the armature f of theresistance deviceA to the left, as in the first instance, it should bethrown over in the opposite direction, shunting the coil 6 and thecurrent would then pass through the coil e attracting its armature intothe position shunting the same, the circuit would then be cleared of allof its interposed resistance over the said shunt b and b and the passageof the current would then be confined to this part of the circuit in thesame manner by the remaining resistances on both sides; and that thesame operation can be performed from any one of any number of crossshunts comprising such a circuit, and further, upon. the circuit beingcleared of resistances for the passage of currents from one cross shuntin the circuit either to the left or right hand side of the same, that,if this nearest cross shunt is opened or switched out of the circuit,to-

gether with its resistance device in the circuit, the same operation canbe repeated for this also, extending the circuit for the passage of thesucceeding current impulse to the second nearest cross shunt, whichagain can be opened, or, with its resistance cut out of the circuit; thecircuit is again extended forthe passage of another current impulseoperating in the same way on the third cross shunt, and so on for anynumber of such cross shunts desired, and the method and devices employedwill be described in the following.

The diagram, Fig. 5, shows one of the cross shunts 6,1), 6 6 of Fig. 4,with an inductively. operated switch consisting .mainly of an armature jpivoted and electrically connected with the lower part of the crossshunt b at its lower end, and a coil and its soft iron core 6* in thecircuit of cross shunt 6 which, upon the passage of a current in eitherdirection, will attract the said armature There are also, the twobranches h, 71., both oi which connect with the main branch (4, one oneach side of the resistance device A as shown, and terminating with thecontact springs 7L and if, which are in the form shown, with theircontact points normally separated from each other by their tension. Thesprings 7L2, [L3, are brought in contact with each other by the tappet72" on the armature j, which tappet is of hard rubber, or the armature jis by other means insulated from the said branches b 72., which, throughthe contact of said springs [L2, [L3, shunts both coils of theresistance device A. out of the circuit of the main branch a when thearmature j is in the position of the dotted line. As shown, theresistance device A and the position of the armature j are in theposition of rest, with both coils of the resistance device A in thecircuit, and the armature j closing the cross shunt b and with the saidshunting branches h it open.

Referring to Fig. i, if all of the cross shunts 6, Z), 6 6 etc., of sucha circuit were provided with means for opening them, as in Fig. 5, andalso with such shunting branches h h, the latter, when the cross shuntof the circuit to which they belong is opened, will be closed, therebyshort circuiting the entire resistance device belonging to that crossshunt, and ii? the shunting armature f is thrownover to shunt the coilof the resis"ance device on that side of the cross shunt in thedirection in which it is desired to prepare the circuit for the passageof currents, vhich as before, we will say isto the left, and the key kis depressed an instant, as before, the current impulse will passthrough the resistance coil 6 and the nearest shunt b, throwing theshunting armature f into its shunting position, shunt ing the saidresistance coil 6 out of the cir cuit, as was described; said currentimpulse will now also pass through the coil i at said point 5,corresponding to the coil 5*, at shunt 6 Fig. 5, thereby attracting thearmature j, throwing it over into the position of the dotted lines, inwhich position its insulated tappet h will close the shunt it h, therebycutting out the resistance A and at the same time, open the contact ofits other (electrically connected) tappet 71 with the spring 6, wherebythe cross shunt b is opened, and the cross shunt Z) is now the nearestclosed cross shunt to that in which the current is generated, and withboth of the resistance coils oi the cut out cross shunt 7) out of thecircuit. Now if we suppose the main circuit extends beyond cross shuntZ) with any. number of similar cross shunts which are each provided withsimilar means for cutting them out of the main circuit, allother currentimpulse sent out from the current generator 13 will open and cut itsresistances out of the circuit in the same manner as was described forthe cross shunt Z); and this canbe repeated for as many cross shunts asmay be desired until the cross shunt desired to be reached is the onenearest to the current source of those remaining in the circuit on thatside of the same.

The desired point of the circuit having been selected, currents can nowbe sent in either direction over the main branches at and 0 between thesaid two points, with all of the intervening resistance devices cut outof the same, and regardless of how many of the intervening cross shuntshave been opened, there remains in the intervening circuit none but theresistance of the conductors, with the exception of the first resistancecoil of the selected cross shunt, which still remains; but one currentimpulse will throw the shunting armature of the resist ance devicebelonging to this cross shunt, over into the position to shunt said coilout of the circuit also. This current impulse, as well as all other andsucceeding currents for other purposes, must be of a lower currentstrength or of shorter duration so as not to throw the armature j, asshown in Fig. 5, over into the position to open the cross shunt in whichit is placed, and for this purpose, this armature j is made somewhatheavier so as to give it the required inertia. The latter descriptionapplies to the inductively operated switching or cutting out arrangementas shown in Fig. 5, or any form of the same which may be employed, inwhich currents operate such switching arrangements in both directions.Later, however, will be shown a polarized device for this purpose bywhich the selecting operation will be performed by currents in onedirection only, and currents of any strength desired can be sent overthe selected part of the circuit in the opposite direction, withoutaffecting the selecting devices of the circuit. Such polarized switchingdevice is equally adapted to open the shunts shown in Figs. 4c and 5,but would require generators of currents of both polaritiesv as will beshown later.

I will now describe the means for restoring the circuit referring toFig. 6. The cross shunt I) connected to the main branches a and 0 withits resistance device A, coil z' shunting branches h" h, and armature 7'with its insulated tappet h which in one position opens the branch h h,are all practically the same as the cross shunts described in connectionwith Figs. 4c and 5. The armature j is pivoted in the middle and iselectrically connected with the main branch 0 a of the coils z' and i.

at its middle and pivotal part, and connects the shunt Z) with the saidmain branch cby contact in the position shown. The said armature j isheld to its two extreme posi tions by itsweight predominating above thefulcrum; A third main branch a similar to the main'branch a, is providedwith like cross shunts b, resistance devices A, main circuitshuntingbranches h fi and coils i which alternately with the coil z' change theposition of the. common armature. j, which alternately makes contactwith the cross shunts Z) and Z), one of which is employed to restore theconnection of the other, the armature j making contact with one, whileit. opens that of the other, and holds the main line or branchzshunt *h"72. open, while those of the other branch are allowed to close. Thismethod-of restoring will be further shown and described in connectionwith the, polarized switching device in place A circuit such as shown inFig. 6, maybe provided withcurrent generators for each cross shunt asthe battery B and contact. keys 7c and is as shown, for sending currentsover the circuit to the nearest closed cross shunts in the circuit tothe right or left of it, either for selecting, we will say, over thebranches a and 0 by the key is, or for restoring the'opened cross shuntsconnecting said branches or. and

a over the branches 4i and 0 by depressing i the key 70*.

. In the diagram Fig. 7 is shown the manner of opening the cross shuntsb b etc., in a circuit, such as shown in Figs. 42 and 5, by employing apolarized switching device in place of the magnet i and armature j astherein shown, such polarized switching d'evice being shown more fullyin Fig. 8. In

Fig. 7 the permanent magnet in of Fig. 8 is leftout for the sake ofclearnes's,'showing only the two cores and their respective coils 2 d",and the armature j, which has its upper end weighted to insure holdingit to its positions,. although the pull "of the permanentmagnet on theend of the said armature j, through that one of the soft iron coresofthe same which is nearest toits-core, tends to hold the said armature jto either vof its two positions even when no current is flowing. Thesaid armature j is electrically connected at its central or pivotalpoint to the terminal of one branch of the cross shunt b, which branchis indicated by 6 and makes contact, when in the position shown, withthe other. terminal in said branch 6 having the coils -i 5, in circuitand connects through the tensionally closed key 79 with the resistancedevice A, belonging to this cross shunt, and the main branch at, theother end of this branch '6 connecting through the other key is with themain branch 0 as shown. A current generator is provided for each of the.cross' shunts in.

such circuit for sendin'g current impulses of either polarity into thecircuit for the purposeof seleotionas has "been described, such currentgenerator being indicated by a battery B and the contact keys is and kwhose connections with the said-battery B are such that, when both ofthe said keys Jo reand attracting either end of the armature 7'according to the polarity of such current; thus, incoming currents ofone polarity, when the armature j isin the position of rest as shown,will: not change its position, leaving the cross shunt .in which it'isplaced, closed, and the shunting branches h and 71. (whose functionswere described'in connection with Figs. 5' and 6) open, while if theincoming currentisof the opposite polarity, it will change the armature9' over .to its opposite position, thereby opening-its contact with thecoil terminalof the said branch 5 opening thecross shunt, and itsinsulated tappet h will close the springs 71 and'lfi,

[thereby shunting the resistance device A out of the main branch a, ashas been explained. The further arrangements of the battery connectionsare such that the outgoing currentsof one polarity sent into the circuitby depressing the key k xwill passthrough the cross shunt b, the otherbranch of the same, 6 which has the coils 11 i in circuit, being thenopen. Upon depressing the key is, currents of opposite polarity will besent into the circuit, and this will pass through the branch 6 with'thecoils i a in circuit but the polarity being such. as not to change theposition of'arm'ature j, or to make any change in the selective .partsof .the'circuit at this point.

Referring to Fig. 8, it will be seen, that the polarized device, whichwill in the following descriptions be designated by the letter C, is ofthe nature ofa polarized ringer as ordinarily "used in telephoneinstruments and will be readily understood without further descriptionof the same. It will be-noticed further on that instead of closing (oropening) the shunting branches of the armature j directly through thetappet h, and also the same in opening and closing the shunt b by itsown contact, the said armature j may only be employed through its tappet71/ to .close 'a pair of springs similarly as is shown in Figs. 7 and 8,butsuch being the terminals of an independent electric circuit having abattery or other current source, whose circuit upon being closed by suchpair of springs as k It can be made to operate both the closing oropening of't'he cross shunt b, the closing of the shunting branches h7L, and perform other operations too numerous and requiring more powerthan the armature 9' directly could be made to overcome. The same methodcan also be applied where the several cross shunts of the circuit are.opened by currents of either polarity as shown in Fig. Such a circuitas shown and described in connection with Fig. 4, and the inductivelyoperated cross shunts connecting the two main branches of the same(which cross shunts, with several forms of the inductive means for suchoperation in circuit, and which are shown and described in thesubsequent figures) will require an additional means for restoring suchcross shunts to their normally closed condition, as when the circuit, orthe part of the same in which a particular cross shunt islocated, is atrest. This will be required whether the opening of such cross shunts iseiiected by the polar ized inductive switch such as described in Figs. 7and 8, or by means of the simple electromagnet form of the switchingdevice, as shown in Fig. 5, and for which the method of restoring hasbeen shown by Fig. 6. The method employed for operating the severalcross shunts of the circuit when the branches h and 7t and the se aratecross shunts for each, 7) and b which alternately connects with theother main branch of the circuit 0, through the switching or contactlever. Z? and the part of the cross shunt b, which may be considered asa part of the main branch 0, and which alternately c011- nects with theterminals of the pair of cross shunts proper, Zr and 6, through the saidcontact lever 1-. The polarized switching or shunt operating device C isplaced in the circuit in the part; of the cross shunt 5 and 0perates bycurrents of either polarity coming in over the main circuit from othercross shunts or stations) on either side of it; and over either of thecouple of conductors a or n constituting one of the main branches ofsuch circuit, according to whichmember of the pair has its cross shuntZ) or I) contact-,

ed with the said branch 6 through the said switch lever Z", so that thepolarized switching device C is always under control,thr0ugh one or theother of the said members of conductors a or a, fromany one of the othercross shunts in the circuit as has previously been described by passingcurrents of the proper polarity to throw the polarized armature j of thesaid device C over into its opposite position, thereby changing theelectrical connection of the cross shunt from that member of said pairto the other; and this may then be employed to pass a current throughsuch cross shunt of a polarity to throw the said armature j back to itsfirst position, restoring its connection with first member of the pair.As previously explained, currents of one polarity may be passed throughsuch cross shunt without effecting any change in the contacts, and thisis true whichever of the two members of conductors such current arrives:tromv and passes through that part 6 of the cross shunt having theswitching device C in circuit, and common to both of the said members.As both of such members a and a of the pair and their connections arealike, it is immaterial which of them is employed for selection orrestoring, but with reference to the diagram Fig. 9, we will consider aas employed for selecting and the other member a for restoring. Thecross shunt belonging to the selecting member a may then be providedwith a manually operated arrangement for further selection, such crossshunt b being divided into two separate branches 5 and 6 either of whichbranches may be employed at will by changing the lever switch 13 up ordown. The said lever switch 6 is spring held upwardly, and is held downto its lower position, which is its normal position of rest, by adetachable weight, such as the telephone receiver (not shown), closingthe branch 1 and when the said detachable weight is removed, it pressesupward closing the branch 6 (the branch 6 may be the signaling circuitand the branch 2 the speaking and listening circuit of a telephoneinstrument), and it will be evident without further illustration, thatany of the forms of cross shunts herein shown, are adapted for a similarselective arrangement, whether such is shown of the main circuit shunt7L closed, while those of the main circuit shunt h remain open. Thepolarized armature j is also shown in the position of rest of thecircuit, leaving the contact springs m of the relay circuit m open. Thiscircuit m is provided with a battery B, and the coil m wound upon theupper half of the core is in the circuit of the same. Anincomingselecting current passing through the coils of the polarized device C,will throw the armature 7' over into its opposite position, closing thesprin s m of the said relay circuit, and the current flowing willenergize the core wa and attract the end of the con tact lever Z therebychanging the contact from that of cross shunt 5 to the cross shunt b,and allow the contact springs in the main circuit shunt h to open whileclosing the contact springs of the main circuit shunt it. The selectingmember A of the pair with its cross shunt Z is now outout and willremain so as long as thearmature j remains in this position, holding thecontact springs of the relay circuit m closed, and the said member a hasno connection with. the main branch 0 at this point of the circuit andhas its shunting branches it closed, whereby its resistance device A isshort circuited, and presenting no resistance to currents passing overthe said member a past this point; the other member at now beingconnected with the main branch 0 through the coils of the polarizedswitching device C, and having its resistance device A in circuit, (itsshunting branches it being open) a restoring current arriving over thesaid member a from either side, will be compelled, as has beenexplained, to pass through the, shunt Z) and 6, throwing the polarizedarmature 7' back to its first position, and thereby allow the contactsprings or" the relay circuit m to open. The core m being now no longerenergized, the said contact lever Z is released, and falls back by itsweighted end into its first position of rest, and restores the contactof the cross shunt b of the said member a, and closes the shuntingbranches it, while those of h are allowed to open. The said contactlever Z has its weighted end properly insulated at the point where itpresses against the terminal pair of springs of the shunting branches Itand It. The said contact lever Z carries by a light projecting stem thebusy 7 signal 0, to indicate that the selecting cross shunt a is cutout.

A secondary circuit p is shown with the coil 29 wound upon the lowerhalf of the core m and upon the opening of the relay circuit m aninduced current impulse is set up in the said circuit 7), whichenergizes the core p which, as shown, is placed between the tworesistance devices A* and A, restoring their respective armatures f, ifone or both of the same should .be in their shunting position which hasbeen explained. Each of the cross shunts in such a circuit may havecurrent generators in connection, substantially in the same manner as isshown in Fig. 7, switched into the circuit at some point in the part bof each cross shunt. v r

A circuit such as has been described but with the cross sh'untsof thesame having yet a difierent arrangement, isshown in Fig. 10, one suchcross shunt with the adjacent main branches being shown in the diagram.Like the last foregoing, a pair of conductors are employed, but insteadof separate resistance devices and cross shunts for each of theconductors a and 12, between which the connection of the main branch 0is alternately switched, this arrangement consists 'irtually of a singlecross shunt 6 having in circuit the polarized switching device .C'(acting through a relay circuit m like the foregoing) and the resistancedevice A and the relay operated switching lever Z which switches thisterminal of the cross shunt b from one to the other of the saidconductors a and n, obviating the use of one resistance device at eachstation and the main circuit shun ing branches h as previously shown,the main branch conduc tors a and n, with this arrangement, closingautoinaticaly through their respective contact springs i and r (by thetension of the springs) upon the withdrawal of the contact parts of thesaid switching lever Z from between the converging contact points ofsaid spring 1 and 1". The said contact lever Z is weighted on one end bythe soft iron piece Z by which this end is raised by the attraction ofthe core and coil m in the relay circuit m when the same is closed bythe polarized armature j, and drops again by its weight into theposition s iown which is that or rest of the circuit when the said relaycircuit m is allowed to open by the throwing back of the said armatureinto its first position by an incoming current of the proper polarityflowing through the shunt b as has been explained. The construction ofthe said contact lever Z is shown more plainly in the diagram 10, andconsists of two parts Z and Z insulated from each other by fiber orother suitable material shown by Z The ends which engage the pair ofsprings 1"- and 1' are bent at right angles to the main body of thelever as shown (this is not essential as they will serve as well ifstraight). This contact lever Z may be pivoted in the ordinary way bythe two tapering screws 7% Z which are the separate electricalconnections of the two insulated halves of the said lever Z, suchelectrical connection being continued separate through the two branches9 and g to the resistance device A, Figs. 10 and 10 coming togetherthrough the two coils of the same and, continued through the cross shuntb, the other terminal is connected to the main branch 0. by which itwill be evident that, as the said contact lever Z in its two oppositepositions engages and spreads apart one of the pair of springs 2 or r,the two sides (left or right) of the conductor a or a with which thesaid contact lever is engaged is continued separately for both incomingand outgoing currents through their respective insulated sides Z and Zand branches 9 and g and to their respective coils of the resistancedevice A and cross shunt b in the same manner as has'been shown for thecircuit employing" only one single conductor for both of its mainbranches as in Fig. 4. The pair of springs r and r not engaging with thesaid contact lever Z as r Fig. 10 in the position shown of the saidlever Z closes upon each other and the electrical connection of theconductor it continues intact, without any resistance left in the same,past this point of the circuit.

The relay circuit m is made to include the the coil and core 29 whichwhen a current is passing, attracts a pendent pawl 72 which is thus madeto engage with the projection 6 upon the hook switch Z2 (also shown inFig. 9) locking the same to its lower position so long as the relaycurrent is passing, that is, so long as the cross shunt b and b isconnected with the restoring conductor a. As soon as the shunt Z) and Z2is restored to its connection with the selecting conductor a, as hasbeen explained in connection with F 9, the said pawl p falls back to itspendent position again the said relay circuit is then opened again, hasalso been previously explained. The two branches of the cross shunt l)and Z2 alternately in the circuit by the upper and lower position of theswitch. lever b are similar to the arrangement shown in Fig. 9, and thecurrent generator or battery B is placed in the circuit of the branch 6as shown, which together with the battery circuit and pole-changing keys7'; 7a, are for transmitting selecting and restoring currents to eitherside of the circuit as has been previously explained, and will beunderstood without further description. The locking of the switch leverZ2 just described, keeping the said branch b open, prevents the passageof such currents from this point so long as this part of the circuit isemployed from some other part of the same.

ll claim:

1. An electrical selective system, comprising a main circuit havingbetween its two branches a plurality of cross shunt connectionsand'having at the intersection of each shunt with one branch asymmetrical resistance device consisting of coils having their oppositeend connected respectively to the contiguous parts of the same branch ofthe main circuit and having each cross shunt connection, between the twobranches of the main circuit, connected to the windings of theresistance coils at a point between their opposite ends, and means forsuccessively extending the main circuit past the several shunts.

2. An electrical. selective system, comprising a main circuit havingbetween its two branches a series of cross shunt connections and havingat the intersection of each shunt with one of its branches a symmetricalresistance device consisting of coils having their opposite endsconnected respectively to the contiguous parts of the same branch of themain line, and having the series of cross shunt connections eachconnected at one end to the coils at points between their opposite endsand a series of cut-out devices between the other ends of the crossshunt-s and the other branch of the main line, whereby each cross shuntis successively opened by successive impulses along the main line untilthe circuit of the desired cross shunt is reached.

3. An electrical selective system, comprising two main line branches anda return branch, a series of cross shunt connections between each mainline branch and the return branch, a series of resistance deviceslocated at the intersection of each main line branch and cross shunt,each resistance 'device consisting of two coils, the opposite ends ofwhich are connected to the contiguous parts of the main line branchesand the cross shunts being each connected to the reristance devicesbetween their two coils, a double acting and oppositely acting cut-outdevice between the several cross shunts and return branch, said doubleacting cut-out device opening the cross shunt on one side of the mainreturn branch and closing the'corresponding cross shunt on the otherside, and a circuit closer for each main branch for effecting selectionand restoring the parts to the position of rest.

a. An electrical selective system, comprising two main line branches andan interme diate return branch, a series of cross shunt connectionsbetween each main line branch and the intermediate return branch, aseries of resistance devices located at the intersection of each mainline branch and cross shunt, each resistance device consisting of twocoils having their opposite end connectcd to the contiguous parts of themain line branches and the cross shunts being each connected to theresistance devices between their two coils, a cut-out device between theseveral cross shunts and return branch for each main line branch, thecutout device for one main line shunt acting reversely to the cut-outdevice for the other main line shunt, one being arranged to restore theother, and a separate circuit closer for each main line branch.

5. An electrical selective system, comprising a main circuit havingbetween its two branches a cross shunt connection and having at theintersection of the shunt with one branch, symmetrical resistance deviceconsisting of two coils having their opposite ends connectedrespectively to the contiguous parts of the same branch of the maincircuit and having one end of the cross shunt connection connected tothe resistance device between its two coils and a double acting cut-outfor the other end of the shunt arranged to both open the cross shunt andcut-out the coils of the resistance device" from the main line.

a 6. An electrical selective system, com prising a-plurality of crossshunts respectively connecting at each station two main branches of an.electric circuit one of which is a common return branch and the otherbeing composed of any number of separate conductors interchangeablyconnected to the common return branch through their re spective crossshunts at each station, a symmetrical resistance and inductive deviceconsisting of a coil in two parts for each con ductor at each station,having the cross shuntconnection to the winding of the coil at apointbetween the two parts and having the opposite ends connectedrespectively to the contiguous parts of their respective conductors, acoil shunting armature interposed betweenthe two parts of the combinedresistanceand inductive coil, an inductive means in the circuit of eachof the several -cross shunts operated by current impulses from the maincircuit opening the connectIOIIOf ltS shunt withthe common return branchand interposes that of one of the other members of interchangeableconductors constituting the other branch of the circuit. I

7 An electrical selectivesystem comprising amain circuit having a seriesof cross shunts one for each station, connecting two main branches oneof which is a'common return and the other being composed of a pluralityof interchangeable conductors or members, each having for the severalstations two terminal springs, for the two sides of the circuit pressingagainst each otherand normally closing the several m'emi bers'orconductors when having no cross shunt connection at this point past eachstation, a symmetrical resistance device at each station consisting of acoil, the opposite ends of which are inserted betweenthe terminalsprings of one of the" members constituting. ons of the main branches,to

respectively contact with the two sides of the circuit, and having thecross shunt connection with the-coil at a point between its oppositeends, and an inductive meansin the circuit of each cross shunt operatedby cur: rent impulses from the main circuit changing the connection ofthe single return branch through its shunt connection from onetotheother ofthe members or separate conductors constituting the othermain branch of the circuit. a

8.1541 electrical selective system, comprising a main circuit having aseries of cross shunts, one for eachrstation, connecting two mainbranches oneof which is a common return and the other. being'composed ofa plurality of interchangeable conductors or members, each having forthe several stations two terminal springs, for the two sides of thecircuit pressing against each other and normally closing the severalmembers :polarizedinductive means in the circuit of eachcrossshuntrequiring for its operation current impulses of one polarityand which is inoperative for'current impulses of'opposite polarity.

9. The selectiveresistance device, comprising the junction of threeconductors or' branches, two of which may be the contiguous parts of themain branch of a circuit and the third branch ashunt, a combinedresistance and inductive coil in each of the twobranches constitutingthe main circuit, an oscillating coil shunting armature interposedbetween the two coils having pivotal 'or rocker seat electricalconnection to the junction of the three branches of conductors and inits two extreme and opposite positions making contact with one or theother of the" two branches of the main circuit at a point beyond itscoil shunting the coil on the side to which it isattracted by theenergizing of the. coil upon the first arrival of a selective currentimpulse from that side ;of the circuit, and means forrestoring thearmature from either 01? its shunting positions to its neutral or middleposition.

10. An electrical selective system, comprising a main circuit havingbetween its two branches a series of cross shunt connections, one of thebranches consisting of a plurality of interchangeable members, one

of whichis always connected to the other or common return branch throughthe several shunt connections and having at the intersection of eachcross shunt with one of the interchangeable member a symmetrical:resistance device consisting of a coil wound in two parts having itsopposite ends connected respectively to the'contiguous parts of one ofthe mexn bers of which one of themain branches of thecircuit is composedand having the cross shunt connection to the coil at a point between itsopposite ends, acoil shunting armature interposed between the twopartsfof the coil, shunting that part of the same out of the circuit onthe side from vwhich an incoming selective current impulse arrives,leaving two such parts of coils remaining 1n the main circuit betweenthe cleared cross shunt and the nearest shunt in i the circuit beyondit; '1

1l. An electrical selective system, com

prising a main circuit having between its two branches a series ofcrossshunt connec tions, one of the branches consisting of a plurality ofinterchangeable members one of which isalways connected to the other orcommon return branch through the several shunt connections and having atthe intersection of each cross shunt with one of the interchangeablemembers a symmetrical re sistance device consisting of a coil wound intwo parts having its opposite ends connected respectively to thecontiguous parts of one of the members of which one of the main branchesof the circuit is composed and having the cross shunt connection to thecoil at a point between its opposite ends, a suitable current source inconnection with each of the. several cross shunts, a coilshuntingarmature interposed between the two parts of the double coil shuntingthe part of the coil out of the circuit in the direction in which anoutgoing selective current is desired to be sent, means for throwing thecoil-shunting armature to the proper shunting position for the outgoingcurrent, two such parts or coils remaining in the circuit behind theapplied current to the nearest cross shunt behind it and one such partremaining in the circuit in the direction of the outgoing current, meansfor, shunting the remaining part of the coil out. of the circuit cleaing the same to the nearest cross shunt connection, means forsuccessively shifting the nearest and then the following cross shuntstogether with their respective resistance devices to another member ofthe interchangeable conductors of which one of the main branches iscomposed, and means for restoring through the other member and in asimilar manner the cross shunt connections and their respectiveresistance devices when desired.

12. An electrical selective system, comprising a main circuit havingbetween its two branches a plurality of cross shunt connections one ofthe branches consisting of two interchangeable members one of which isalways connected through the several common cross shunts to the othersingle or common return branch and having at the intersection of eachcommon cross shunt withone of the interchangeable members a symmetricalresistance device consisting of a coil in two parts having the shuntconnection and a coil-shunting armature connected to the winding of thecoil at a point between the two parts of the double coil the oppositeends of which respectively are interchangeably connected to the oppositesides of the circuit of one or the other of the two members of theinterchangeable branch, a contact lever consisting of two longitudinaland insulated parts respectively connected to the opposite ends of theresistance coil and'constituting the contact terminals of the same, apair of contacts and circuit closing springs for each member at eachstation, terminals for the opposite sides of the circuit, andinductively operated means for switching the contact lever from onemember and inserting the insulated contact parts of the same between theself-closing contact springs of the other member, the

shunt being restored through the other.

, 13. An electrical selective system, comprising a main circuit havingbetween its two branches a plurality of cross shunt connections andhaving at the intersectionof each shunt with one branch-a symmetrical,resistance device consisting of coils having their opposite endsconnected respectively to the contiguous parts oi the same branch of themain circuit and having the cross lshunt connection, between the twobranches *ings of the resistance coil at a point between its oppositeends, the several cross shunts for a part of their length con- ,sistingof two branches, an upwardly aspriug-held selective contact lever heldto Eits lower position by removable weight and having pivotal orothewise electrical connection. with the other and single terlminal ofthe cross shunt, its upper and :lower positions contacting respectivelywith .two branched terminals of the cross shunt, and inductivelyoperated means for temporarily locking the contact lever to its lowerposition. i e 14:. An electrical selective system, comprising a maincircuit having between its two branches a series of cross shuntconnections, a plurality of interchangeable members for one of the mainbranches of the circuit interchanging with, each other through theseveral cross shunt connections with the other single or return branch,a symmetrical resistance device consisting'of coils having theiropposite ends respectively connected to the contiguous partsofthecircuit of one of the interchangeably operated members constitutingone of the main branches of the cricuit, and having the cross shuntconnection and a coil-shunting armature connected to the winding at apoint between the two coils, a continuous current generator in consitepole branches having respectively two contact points approaching eachvother but having a suitable space between them, two springs respectivelyfor the two terminals of the open cross shunt interposed between acontact point from each of the opposite generator pole branches, bothsprings nor- ,mally contactingwith the same generator connection of onemember to the commonof the main circuit, connected to the-windnectionwith each cross shunt whose oppopole branch through which the crossshunt is closed with the generator out of the circuit but changedcontact of one of the cross shunt" springs to the opposite generatorpole branch brings the generator into the shunt circuit with currents inone direction and with the'change of contact of the other terminalspring the generator is connected to the shunt in the oppositedirection, and means for operating the two cross shunt terminals (7c 70,Figs. 9 and 10).

15. An electrical selective system, comprising a main circuit havingbetween its two branches a series of cross shunt connections each ofwhich has in connection a current impeding means in the main circuitbetween each of the several cross shunt connections capable of beingshunted orcutout of the main circuit in the direction of the same-inwhich the selection of a cross shunt connection'is desired, and meansfor cutting or shunting such current impeding means out of the circuit.

16. An electrical selective system, com prising a main circuit havingbetween its two branches a series of cross shunt connections each ofwhich has in connection a current impeding means in the main circuitbetween each cross shunt connection, the cross shunt together with thecurrent impeding means capable of being cut out of the circuit, andinductive means in'the circuit-of each cross shunt for successivelycuttingall cross shunt connections together with their frespectivecurrent impeding means out of the main circuit between the cross shuntin which the selecting current is applied and the circuit of the crossshunt to be selected.

17. An electrical selective system comprising a main circuit havingbetween its two branches a plurality of cross shunt connections, one ofthe branches being composed of a plurality of interchangeable members orsimilar and separate conductors, while the other branch of the maincircuit with its several cross shunt connections constitutes a commonreturn branch, current impeding means in the main circuit between eachcross shunt connection which together with the cross shunt is capable ofbeing cut out of the circuit of one of the several interchangeablemembers of the plurally constituted branch of the main circuit andinserted into the circuit of another member of the same branch, andinductive means in the circuit of each of the several cross shunts forsuccessively cutting all cross shunt connections together with theirrespective current impeding means out of the circuit of one member of rthe plurally constituted branch of the main circuit and inserting thesame into the circuit of another member of the same branch between thecross shunt in which the select-,

N. S. BosoM, T. W. Fnnnnns.

fcopies of this patent may be obtained for five cents each, byaddressing the Commissioner of Patents,

3 Washington, D. C.

